1. Field of the Invention
The present invention is generally in the field of electronic devices. More particularly, the invention is in the field of battery and power management for electronic devices.
2. Background Art
Many modern electronic devices that are powered by a battery implement some method of monitoring the battery to estimate battery run time. For example, cellular telephones, portable media players, digital cameras, and other portable electronic devices each typically include a system for monitoring the battery coupled to the device. Presently, two types of systems are commonly used. The first type of system measures the battery voltage, and provides that battery voltage to the device for use in estimating the battery run time. The second type of system tracks the charge applied to and taken from the battery, and provides that information to the device for use in estimating the battery run time. Both types of conventional systems have attendant drawbacks.
For example, conventional systems that monitor battery voltage can provide only rough battery run time estimates because the relationship between battery voltage and battery capacity typically varies according to the load placed on the battery by the device. The load placed on the battery may vary dynamically depending on what function the device is performing, thus making battery capacity and run time estimation difficult. The second type of system, which tracks the charge applied to and taken from the battery, tends to be more expensive to implement than the first type of system, and is typically implemented in the battery of a device, instead of in the device itself, because otherwise tracked charge will become inaccurate when batteries are replaced. This type of system can also suffer inaccuracies when tracked batteries are not deeply discharged and then fully charged.
Thus, there is a need in the art for a method for accurate battery run time estimation that overcomes the disadvantages associated with utilizing conventional systems.